1. Field of the Invention
The present invention relates to a multilayered sliding material of lead bronze containing graphite and to a method of manufacturing the same, this material being suitably used for bearings, bushes, and washers employed in automobiles, industrial machines, agricultural machines and so on.
2. Description of the Related Art
In the above-described fields, the main portion of the multilayered sliding material used for bushes and washers comprises bimetal type sliding materials comprising a steel back plate and a sintered alloy such as Cu-Sn-Pb type or Cu-Sn-graphite type, these materials having hardness of Hv 60 to 100. A sintered alloy having a hardness exceeding Hv 100 is used in a bimetal type sliding material comprising phosphor bronze and a steel back plate, this phosphor bronze containing neither lead nor lubricant. In the conventional bimetal type sliding material comprising a steel back plate and a sintered alloy there is used Cu-Sn-Pb or Cu-Sn-graphite sintered alloy which contains 10 to 30 wt% Pb and 2 to 8 wt% graphite. However, the recent advancement of the internal combustion engines requires a bearing material of the type capable of bearing higher pressures in comparison with the conventional bearing materials which is poor in load durability when bearing a higher pressure. On the other hand, the bimetal of the sintered alloy of phosphor bronze encounters a problem of poor seizuring resistance although the same has an excellent durability against load.